title: Delineation of the translocation of colicin E7 across the inner membrane of Escherichia coli.
abstract: The lysis protein of the colicinogenic operon is essential for colicin release and its main function is to activate the outer membrane phospholipase A (OMPLA) for the traverse of colicin across the cell envelope. However, little is known about the involvement of the lysis protein in the translocation of colicin across the inner membrane into the periplasm. The introduction of specific point mutations into the lipobox or sorting signal sequence of the lysE7 gene resulted in the production of various forms of lysis proteins. Our experimental results indicated that cells with wild-type mature LysE7 protein exhibited higher efficiency of colicin E7 translocation across the inner membrane into the periplasm than those with premature LysE7 protein. Moreover, the degree of permeability of the inner membrane induced by the mature LysE7 protein was significantly increased as compared to the unmodified LysE7 precursor. These results suggest that the efficiency of colicin movement into the periplasm is correlated with the increase in inner membrane permeability induced by the LysE7 protein. Thus, we propose that mature LysE7 protein has two critical roles: firstly mediating the translocation of colicin E7 across the inner membrane into the periplasm, and secondly activating the OMPLA to allow colicin release.
authors.affiliation: Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
authors.forename: Yuh-Ren
authors.initials: YR
authors.lastname: Chen
authors.forename: Tsung-Yeh
authors.initials: TY
authors.lastname: Yang
authors.forename: Guang-Sheng
authors.initials: GS
authors.lastname: Lei
authors.forename: Lung-J R
authors.initials: LJ
authors.lastname: Lin
authors.forename: Kin-Fu
authors.initials: KF
authors.lastname: Chak
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003087:Colicins / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009876:Operon; D019897:Periplasm / Q000378:metabolism; D054466:Phospholipases A1 / Q000378:metabolism; D021382:Protein Sorting Signals; D021381:Protein Transport
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003087:Colicins; D004075:Diglycerides; D029968:Escherichia coli Proteins; D021382:Protein Sorting Signals; C560213:lysis protein, E coli; D054466:Phospholipases A1; C412876:outer membrane phospholipase A